DMS Materials

Diluted magnetic semiconductors (DMSs) are materials with magnetic elements embedded in semiconductors. DMSs have been extensively studied in last decade for their unique semiconducting and magnetic properties. Recently, study of DMSs is a very interesting subject due to promising applications to spintronics. Spintronics (spin + electronics) is the technology that transforms reading and writing information by spin rather than by electron charge.

Zinc oxide (ZnO), technologically, is an important material due to its wide range of optical and electrical properties as well as semiconductor crystal with a large exciton binding energy and wide band gap. Recently, ZnO has been recognized as a promising candidate for a dilute magnetic semiconductor when doped with transition metal elements with possibilities of presenting room temperature ferromagnetism with large magnetization. Development of new applications for ZnO has been an integral part of research for the last decade. Current applications for ZnO include catalysis, cosmetics and optical devices.

This work reveals the growth, structural, physical, magnetic and optical characterizations of some transition metal doped zinc oxide with various concentrations. This research work shows that the successful doping of transition metal ions in ZnO can be achieved. The structures have been analyzed from X-ray powder diffraction technique through Rietveld fitting method. The charge density analysis has been carried out with maximum entropy method, magnetic properties by analyzing hysteresis curves obtained from vibrating sample magnetometer and optical study by UV visible spectrum.

Research Materials

1. Si  

2. Ge  

3. Ge1-xMnx (x = 0.03 and 0.07)

4. Zn1-xCoxO (x = 0.01: Annealing temperature, T = 500°C, 600°C, 700°C, 800°C and 900°C)

5. Zn1-xNixO (x = 0.01, 0.02, 0.03, 0.04 and 0.05)

6. La0.67Sr0.22Mn1.11-xCoxO3 (x = 0.0, 0.02, 0.05, 0.2 and 0.3)

Charge density of Ge0.93Mn0.07 in the unit cell (Iso-surface level = 0.42)
One-dimensional variation of electron density along [100], [110] and [111] of Ge0.97Mn0.03 unit cell
Rietveld refined profile for Zn0.99Co0.01O at 500ºC
Charge density of Zn0.99Co0.01O in the unit cell at 500ºC
The grown sample of La0.67Sr0.22Mn1.11-xCoxO3 (x=0.00, 0.02, 0.05, 0.20 and 0.30)
Rietveld refined profile for La0.67Sr0.22Mn1.11-xCoxO3 at x = 0.00
Charge density of La0.67Sr0.22Mn1.11-xCoxO in the unit cell Charge density of La0.67Sr0.22Mn1.11-xCoxO in the unit cell at x = 0.05 (Iso surface level = 0.25) at x = 0.2 (Iso surface level = 0.25)
2D MEM electron density distribution of La0.67Sr0.22Mn1.11-xCoxO on the (012) plane for x=0.3 (Contour range is from 0.00 to 1.0 e/Å3. Contour interval is 0.03 e/Å3)